1. Field of the Invention
The present invention relates to a coordinate detecting method and system, more particularly, to a coordinate detecting method and system for a touch panel.
2. Description of the Related Art
The conventional coordinate detecting methods for the touch panels include a touching matrix coordinate detecting method, a non-touching electrical field type or capacitive type coordinate detecting method and divided voltage type coordinate detecting method.
The touching matrix coordinate detecting method utilizes a controller having a plurality of I/O ports to form a plurality of X-axis and Y-axis scanning wires. The controller sends signals to the X-axis scanning wires, and reads signals from the Y-axis scanning wires so that a coordinate position touched by the user can be obtained. Because the method utilizes the I/O ports of the controller and the number of the I/O ports is limited, the number of the X-axis and Y-axis scanning wires cannot be increased and the resolution of the touch panel used in the method cannot be improved.
The non-touching electrical field type coordinate detecting method utilizes a controller having a plurality of I/O ports to form a plurality of X-axis and Y-axis scanning wires. A sensor pen is used to read detection signals and the coordinate position of the sensor pen can be calculated. In the method, the I/O ports of the controller are converted to X-axis and Y-axis scanning wires one after another, or one I/O port is converted to multiple X-axis (or Y-axis) scanning wires. For calculating the position of the pen, the controller must send signals (from level Low to level High) to I/O port according to clockwise and counter-clockwise directions respectively so as to precisely calculate the coordinate position.
In the method, the number of the I/O ports can be reduced by the one to multiple converting method. However, the signals must be sent according to clockwise and counter-clockwise directions respectively, then the sensor pen reads detection signals for those two signals. These two detection signals are in the form of voltage gradient, and compared each other in order to calculate the coordinate position. Although the voltage gradient is linear in theory, the voltage gradient is nonlinear in practice. A software program is needed to compensate the nonlinear portion of the voltage gradient. Therefore, the method for calculating the coordinate position is complex.
The divided voltage type coordinate detecting method utilizes a controller having a plurality of I/O ports to form a plurality of X-axis and Y-axis scanning wires. Each X-axis (or Y-axis) scanning wire is connected to a main line formed by the I/O ports. A divided voltage circuit is formed by utilizing the resistance of the main line. Using the method, the number of the X-axis and Y-axis scanning wires is not limited to the number of I/O ports. However, when the controller is powered on, the controller must calibrate the system to reduce the circumference and material interference in the main line. Similarly, the controller must send signals (from level Low to level High) to I/O port according to clockwise and counter-clockwise direction respectively so as to precisely calculate the coordinate position.
In the divided voltage type coordinate detecting method, the few I/O ports are used to form the main line, and the main line is divided into the X-axis and Y-axis scanning wires. However, to overcome the unstable characteristic of the resistance material and the difference in electrical field intensity between the branched nodes, the calculation method is very complex to obtain the coordinate position of the pen. The complexity of software for the divided voltage type coordinate detecting method is higher than that of the non-touching electrical field type coordinate detecting method.
In the above conventional method, the number of the I/O ports is in reverse proportion to the complexity for calculating the coordinate position of the sensor pen. That is, the more I/O ports the controller has, the simpler the calculation method is. The fewer I/O ports the controller has, the more complex the calculation method is.
Therefore, it is necessary to provide an innovative and progressive coordinate detecting method in order to solve the above problem.